Can relaxation, a good night's sleep or happiness come from a lightly carbonated, berry-flavored beverage?

Amid booming sales of energy drinks spiked with caffeine and other stimulating ingredients, some people are heading to the soda aisle for drinks that promise the opposite effect. With names like Neuro Bliss, Marley's Mellow Mood (as in Bob), and Just Chill, the products aren't marketed as medicine, but as a way to relax without turning to more traditional, if sometimes imperfect, measures like taking prescription drugs or having a few beers.

Consumers are warming up to drinks that could fill the chasm between taking medication for anxiety or sleep problems and doing nothing, says Paul Nadel, president of Neuro Drinks, a Santa Monica, Calif.-based company that sells a line of six drinks including Neuro Bliss, Neuro Sleep and Neuro Sonic, an energy drink. He says the 'overmedicated culture we live in' has primed consumers for the concept of a relaxation drink.

Small studies show that some of the ingredients in relaxation drinks, like melatonin, valerian root and L-theanine, appear to help fight sleeplessness or to create a sensation of relaxation in isolated situations.

Still, clinicians recommend turning to drugs or supplements as a last resort for sleep and anxiety problems after trying daily exercise, a consistent wake-up time, turning off electronics and darkening rooms in the evening, therapy or other measures.

The ingredients appear reasonably safe for most adults, but users should check with a doctor or research how they might mix with other medications or pre-existing illnesses, says Catherine Ulbricht, co-founder of Natural Standard Research Collaboration, a Somerville, Mass., group that evaluates natural therapies.

She notes that this class of beverages with multiple active ingredients hasn't been well-studied: 'I don't mean to sound scary, but it's not water.'

Often the drinks are marketed as dietary supplements, a classification under Food and Drug Administration standards that means at least one ingredient isn't considered conventional food. The FDA doesn't review the efficacy, safety or quantity of active ingredients in dietary supplements.

The relaxation drinks come as traditional soda sales continue on an almost decadelong decline and more companies are introducing drinks tailored to niche audiences.

More consumers say they want a drink that feels healthier than soda -- hence the raft of new, lower-calorie beverages. Some have only natural ingredients, while other so-called 'functional' products claim some benefit like energy, sleep or cold-fighting properties.

Big beverage companies are pitching coconut water, energy drinks and fruit smoothies, but so far haven't dipped their toe into the relaxation business.

It's not clear the relaxation drink concept will stick. In 2012 relaxation drinks (which includes sleep drinks) accounted for about $32 million in U.S. wholesale sales, a slight increase from previous years, but a tiny amount compared with the $6 billion generated by U.S. energy drinks the same year, says Gary Hemphill, managing director of research for Beverage Marketing Corp. 'Some people say, 'If I want to relax I'm going to have a martini,' Mr. Hemphill says.

Already a fan of sipping morning coffee to wake up and downing a happy-hour drink to unwind, Patrick O'Brien, a 31-year-old aerospace projectmanager in Los Angeles, recently added two cans of Just Chill to his Monday afternoon routine.

Sold in three beach-themed fruit flavors in a slim can, the drink contains L-theanine, an amino acid found in green tea that the label says 'promotes a Chill Mentality.'

'It's kind of a Xanax in a can,' he says. After a weekend of late nights, the drink helps him feel less anxious confronting a Monday-sized pile of work, he says.

A first round of relaxation drinks came onto the market several years ago. They often were linked explicitly to recreational drug use with names like Purple Stuff and Drank, both slang for the practice of mixing prescription-strength codeine with soda or juice. The drinks now gaining popularity are marketed as mainstream products for busy moms, stressed professionals or those with sleep problems.

Typical consumers 'have too much caffeine, then they grab Just Chill,' to calm down in the afternoon or evening, says Max Baumann, founder and chief executive of the Venice, Calif.-based Chill Group Inc. 'It's not about knocking you out,' says Mr. Baumann. The L-theanine in the drink is meant to focus and relax people before 'anything where there might be a fight-or-flight response,' like a stressful meeting, he says. The company has sponsored yoga and surfing events to cultivate its image, he says.

Some drinks are pitching 'more of a lifestyle thing,' says Lee Brody, global marketing director for Marley Beverage Co., which is owned by Viva Beverages, a Southfield, Mich., company. Members of the Marley family hold an ownership stake.

Three years ago Viva introduced Marley's Mellow Mood drinks, a line of relaxation juices and decaffeinated teas with Bob Marley's image on every bottle. Originally Marley family members came to Viva with the idea of a Bob Marley-themed energy drink, says Mr. Brody. But the 'more authenticproposition for a beverage named after Bob Marley was not energy, but relaxation,' he says.

The company markets the drinks at music festivals like the recent Gathering of the Vibes, in Bridgeport, Conn., a music, arts and camping festival. 'I get asked on a weekly basis, 'Does this drink have ganja in it?' ' says Mr. Brody. (It doesn't.) The drink's appeal is Bob Marley's brand, an association with reggae music and 'hey, take time for you,' in a world of busy schedules, he says. It contains camomile flower and valerian root extracts.

Drinking a sleep beverage 'has to be better than Ambien,' reasons Julie Duffy, an elementary school readingspecialist from Clark, N.J., who drinks Neuro Sleep most nights to fall asleep by 10 p.m., instead of past midnight.